<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>跳转</title>
		<style>
			body{
				text-align: center;
			}
			#sec{
				color: red;
				font-size:25px ;
			}
		</style>
	</head>
	<body>
		<script>
			var number=5;
			var span=document.getElementById('sec')
			function jiang(){
				if(number>0){
					number--;
					span.innerHTML=number;
				}else{
					clearInterval(timer);
					location.href="http://www.runoob.com";
				}
			}
		</script>
	</body>
</html>
